National Geographic explorer and grantee Gregg Treinish wants everyone to know about the hidden toxic cost of synthetic fabrics. Tiny, invisible microplastics are entering our waterways straight from our washing machines. About 2,000 synthetic particles are released from washing a single polyester fleece jacket. All clothing items—including cotton and wool—shed micro-fibers when washed, but the natural fibers biodegrade. Synthetic particles don't degrade and can absorb toxins while traveling through the waterways. If they're eaten by small organisms, such as fish, they can bioaccumulate and end up on our dinner plates.